U.S. Pat. No. 4,581,412 discloses crosslinkable compositions that are copolymers of fluoromonomers and functionalized monomers. They are applied, as aqueous emulsions or in solvents, to substrates and then crosslinked.
patent application JP 52-87231 A discloses a similar coating, but applied to a material not yet crosslinked.
The coatings obtained have good properties due to the presence of fluoromonomers, but they are of the paint or varnish type and have nothing to do with a PVDF film bonded to a substrate. In particular, these coatings have a weatherability which is inferior to that of PVDF films bonded to a substrate.
U.S. Pat. No. 4,364,886 discloses a substrate made of ABS or of a thermoset based on an unsaturated polyester covered with a PVDF film, and an adhesive is placed between the PVDF and the substrate. This adhesive is either PMMA or a blend, by weight, of 30% of PMMA, 40% of an acrylic elastomer, 25% of ABS and 5% of a zinc oxide/zinc sulphide mixture.
Patent Application JP 52-20907 A discloses a structure comprising, in the following order: a layer of uncrosslinked resin mixed with glass fibres, a sheet of glass fibres or polyester fibres, and then a layer consisting of an acrylic ester or vinylidene fluoride resin.
These structures do not exhibit sufficient adhesion of the PVDF layer. It has now been found that it is possible to coat substrates made of a thermoset with a film of PVDF, PMMA or a PVDF/PMMA blend provided that a layer based on a functionalized PMMA is placed between this film and the substrate. It has also been discovered that these films can be used in the SMC technique (this term is described later).
U.S. Pat. No. 5,242,976 discloses a composition that can be coextruded with PVDF in order to make it adhere to substrates that may be of polyester. The composition is a blend, by weight, of 27 to 50% PMMA, 17.5 to 36.5% PVDF and 25 to 47.45% of an acrylic elastomer. The PMMA may contain a monomer chosen from styrene, alpha-methylstyrene, acrylonitrile and (meth)acrylic acid. It has now been found that for there to be adhesion to the thermoset, the PMMA must be functionalized.